A 40-MHz double differential-pair CMOS OTA with-60-dB IM3

Abstract

A configuration of a linearized operational transconductance amplifier (OTA) for low-voltage and high-frequency applications is proposed. By using double pseudodifferential pairs and the source-degeneration structure under nano-scale CMOS technology, the norlinearity caused by short channel effect from a small feature size can be minimized. A robust common-mode control system is designed for input and output common-mode stability and thus reduces distortion caused by common-mode voltage variation. Mining ability can be achieved by using MOS transistors in the linear region. The linearity of the OTA is about -60-dB third-order inter-modulation (IM3) distortion for up to 0.9 V-pp at 40 MHz. This OTA was fabricated by the TSMC 180-nm deep n-well CMOS process. It occupies a small area of 15.1 X 10(-3) mm(2) and the power consumption is 9.5 mW under a 1.5-V supply voltage.